[PATCH v4] Input: sysrq - DT binding for key sequence

[PATCH v4] Input: sysrq - DT binding for key sequence

[mathieu.poirier]

From: "Mathieu J. Poirier" <mathieu.poirier@linaro.org>

Adding a simple device tree binding for the specification of key sequences.
Definition of the keys found in the sequence are located in
'include/uapi/linux/input.h'.

For the sysrq driver, holding the sequence of keys down for a specific amount of time
will reset the system.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
changes for v4:
  - Moved seach of reset sequence nodes to a single call.
---
 .../devicetree/bindings/input/input-reset.txt      | 34 ++++++++++++++
 drivers/tty/sysrq.c                                | 54 ++++++++++++++++++++++
 2 files changed, 88 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/input-reset.txt

diff --git a/Documentation/devicetree/bindings/input/input-reset.txt b/Documentation/devicetree/bindings/input/input-reset.txt
new file mode 100644
index 0000000..79504af
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/input-reset.txt
@@ -0,0 +1,34 @@
+Input: sysrq reset sequence
+
+A simple binding to represent a set of keys as described in
+include/uapi/linux/input.h.  This is to communicate a
+sequence of keys to the sysrq driver.  Upon holding the keys
+for a specified amount of time (if specified) the system is
+sync'ed and reset.
+
+Key sequences are global to the system but all the keys in a
+set must be coming from the same input device.
+
+The /chosen node should contain a 'linux,sysrq-reset-seq' child
+node to define a set of keys.
+
+Required property:
+sysrq-reset-seq: array of keycodes
+
+Optional property:
+timeout-ms: duration keys must be pressed together in microseconds
+before generating a sysrq
+
+Example:
+
+ chosen {
+                linux,sysrq-reset-seq {
+                        keyset = <0x03
+                                  0x04
+                                  0x0a>;
+                        timeout-ms = <3000>;
+                };
+         };
+
+Would represent KEY_2, KEY_3 and KEY_9.
+
diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
index b51c154..01a8729 100644
--- a/drivers/tty/sysrq.c
+++ b/drivers/tty/sysrq.c
@@ -44,6 +44,7 @@
 #include <linux/uaccess.h>
 #include <linux/moduleparam.h>
 #include <linux/jiffies.h>
+#include <linux/of.h>
 
 #include <asm/ptrace.h>
 #include <asm/irq_regs.h>
@@ -671,6 +672,50 @@ static void sysrq_detect_reset_sequence(struct sysrq_state *state,
 	}
 }
 
+static void sysrq_of_get_keyreset_config(void)
+{
+	unsigned short key;
+	struct device_node *np;
+	const struct property *prop;
+	const __be32 *val;
+	int count, i;
+
+	np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq");
+	if (!np) {
+		pr_debug("No sysrq node found");
+		goto out;
+	}
+
+	prop = of_find_property(np, "keyset", NULL);
+	if (!prop || !prop->value) {
+		pr_err("Invalid input keyset");
+		goto out;
+	}
+
+	count = prop->length / sizeof(u32);
+	val = prop->value;
+
+	if (count > SYSRQ_KEY_RESET_MAX)
+		count = SYSRQ_KEY_RESET_MAX;
+
+	/* reset in case a __weak definition was present */
+	sysrq_reset_seq_len = 0;
+
+	for (i = 0; i < count; i++) {
+		key = (unsigned short)be32_to_cpup(val++);
+		if (key == KEY_RESERVED || key > KEY_MAX)
+			break;
+
+		sysrq_reset_seq[sysrq_reset_seq_len++] = key;
+	}
+
+	/* get reset timeout if any */
+	of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms);
+
+ out:
+	;
+}
+
 static void sysrq_reinject_alt_sysrq(struct work_struct *work)
 {
 	struct sysrq_state *sysrq =
@@ -688,6 +733,7 @@ static void sysrq_reinject_alt_sysrq(struct work_struct *work)
 		input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
 		input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
 
+
 		input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
 		input_inject_event(handle, EV_KEY, alt_code, 0);
 		input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
@@ -903,6 +949,7 @@ static inline void sysrq_register_handler(void)
 	int error;
 	int i;
 
+	/* first check if a __weak interface was instantiated */
 	for (i = 0; i < ARRAY_SIZE(sysrq_reset_seq); i++) {
 		key = platform_sysrq_reset_seq[i];
 		if (key == KEY_RESERVED || key > KEY_MAX)
@@ -911,6 +958,13 @@ static inline void sysrq_register_handler(void)
 		sysrq_reset_seq[sysrq_reset_seq_len++] = key;
 	}
 
+	/*
+	 * DT configuration takes precedence over anything
+	 * that would have been defined via the __weak
+	 * interface
+	 */
+	sysrq_of_get_keyreset_config();
+
 	error = input_register_handler(&sysrq_handler);
 	if (error)
 		pr_err("Failed to register input handler, error %d", error);
-- 
1.8.1.2

Re: [PATCH v4] Input: sysrq - DT binding for key sequence

[Rob Herring]

On 07/15/2013 10:36 AM, mathieu.poirier@linaro.org wrote:
> From: "Mathieu J. Poirier" <mathieu.poirier@linaro.org>
> 
> Adding a simple device tree binding for the specification of key sequences.
> Definition of the keys found in the sequence are located in
> 'include/uapi/linux/input.h'.
> 
> For the sysrq driver, holding the sequence of keys down for a specific amount of time
> will reset the system.
> 
> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> ---
> changes for v4:
>   - Moved seach of reset sequence nodes to a single call.
> ---
>  .../devicetree/bindings/input/input-reset.txt      | 34 ++++++++++++++
>  drivers/tty/sysrq.c                                | 54 ++++++++++++++++++++++
>  2 files changed, 88 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/input/input-reset.txt
> 
> diff --git a/Documentation/devicetree/bindings/input/input-reset.txt b/Documentation/devicetree/bindings/input/input-reset.txt
> new file mode 100644
> index 0000000..79504af
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/input-reset.txt
> @@ -0,0 +1,34 @@
> +Input: sysrq reset sequence
> +
> +A simple binding to represent a set of keys as described in
> +include/uapi/linux/input.h.  This is to communicate a
> +sequence of keys to the sysrq driver.  Upon holding the keys
> +for a specified amount of time (if specified) the system is
> +sync'ed and reset.
> +
> +Key sequences are global to the system but all the keys in a
> +set must be coming from the same input device.
> +
> +The /chosen node should contain a 'linux,sysrq-reset-seq' child
> +node to define a set of keys.
> +
> +Required property:
> +sysrq-reset-seq: array of keycodes
> +
> +Optional property:
> +timeout-ms: duration keys must be pressed together in microseconds

milliseconds (ms) or microseconds (us)?

> +before generating a sysrq
> +
> +Example:
> +
> + chosen {
> +                linux,sysrq-reset-seq {
> +                        keyset = <0x03
> +                                  0x04
> +                                  0x0a>;
> +                        timeout-ms = <3000>;
> +                };
> +         };
> +
> +Would represent KEY_2, KEY_3 and KEY_9.
> +
> diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
> index b51c154..01a8729 100644
> --- a/drivers/tty/sysrq.c
> +++ b/drivers/tty/sysrq.c
> @@ -44,6 +44,7 @@
>  #include <linux/uaccess.h>
>  #include <linux/moduleparam.h>
>  #include <linux/jiffies.h>
> +#include <linux/of.h>
>  
>  #include <asm/ptrace.h>
>  #include <asm/irq_regs.h>
> @@ -671,6 +672,50 @@ static void sysrq_detect_reset_sequence(struct sysrq_state *state,
>  	}
>  }
>  
> +static void sysrq_of_get_keyreset_config(void)
> +{
> +	unsigned short key;
> +	struct device_node *np;
> +	const struct property *prop;
> +	const __be32 *val;
> +	int count, i;
> +
> +	np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq");
> +	if (!np) {
> +		pr_debug("No sysrq node found");
> +		goto out;
> +	}
> +
> +	prop = of_find_property(np, "keyset", NULL);
> +	if (!prop || !prop->value) {
> +		pr_err("Invalid input keyset");
> +		goto out;
> +	}
> +
> +	count = prop->length / sizeof(u32);
> +	val = prop->value;

None of the existing helpers to retrieve property arrays doesn't work here?

> +
> +	if (count > SYSRQ_KEY_RESET_MAX)
> +		count = SYSRQ_KEY_RESET_MAX;
> +
> +	/* reset in case a __weak definition was present */
> +	sysrq_reset_seq_len = 0;
> +
> +	for (i = 0; i < count; i++) {
> +		key = (unsigned short)be32_to_cpup(val++);
> +		if (key == KEY_RESERVED || key > KEY_MAX)
> +			break;
> +
> +		sysrq_reset_seq[sysrq_reset_seq_len++] = key;
> +	}
> +
> +	/* get reset timeout if any */
> +	of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms);
> +
> + out:
> +	;
> +}
> +
>  static void sysrq_reinject_alt_sysrq(struct work_struct *work)
>  {
>  	struct sysrq_state *sysrq =
> @@ -688,6 +733,7 @@ static void sysrq_reinject_alt_sysrq(struct work_struct *work)
>  		input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
>  		input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
>  
> +

spurious ws change

>  		input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
>  		input_inject_event(handle, EV_KEY, alt_code, 0);
>  		input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
> @@ -903,6 +949,7 @@ static inline void sysrq_register_handler(void)
>  	int error;
>  	int i;
>  
> +	/* first check if a __weak interface was instantiated */
>  	for (i = 0; i < ARRAY_SIZE(sysrq_reset_seq); i++) {
>  		key = platform_sysrq_reset_seq[i];
>  		if (key == KEY_RESERVED || key > KEY_MAX)
> @@ -911,6 +958,13 @@ static inline void sysrq_register_handler(void)
>  		sysrq_reset_seq[sysrq_reset_seq_len++] = key;
>  	}
>  
> +	/*
> +	 * DT configuration takes precedence over anything
> +	 * that would have been defined via the __weak
> +	 * interface
> +	 */
> +	sysrq_of_get_keyreset_config();
> +
>  	error = input_register_handler(&sysrq_handler);
>  	if (error)
>  		pr_err("Failed to register input handler, error %d", error);
> 

Re: [PATCH v4] Input: sysrq - DT binding for key sequence

[Mathieu Poirier]

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On 15 July 2013 20:43, Rob Herring <robherring2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

> On 07/15/2013 10:36 AM, mathieu.poirier-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org wrote:
> > From: "Mathieu J. Poirier" <mathieu.poirier-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> >
> > Adding a simple device tree binding for the specification of key
> sequences.
> > Definition of the keys found in the sequence are located in
> > 'include/uapi/linux/input.h'.
> >
> > For the sysrq driver, holding the sequence of keys down for a specific
> amount of time
> > will reset the system.
> >
> > Signed-off-by: Mathieu Poirier <mathieu.poirier-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> > ---
> > changes for v4:
> >   - Moved seach of reset sequence nodes to a single call.
> > ---
> >  .../devicetree/bindings/input/input-reset.txt      | 34 ++++++++++++++
> >  drivers/tty/sysrq.c                                | 54
> ++++++++++++++++++++++
> >  2 files changed, 88 insertions(+)
> >  create mode 100644
> Documentation/devicetree/bindings/input/input-reset.txt
> >
> > diff --git a/Documentation/devicetree/bindings/input/input-reset.txt
> b/Documentation/devicetree/bindings/input/input-reset.txt
> > new file mode 100644
> > index 0000000..79504af
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/input/input-reset.txt
> > @@ -0,0 +1,34 @@
> > +Input: sysrq reset sequence
> > +
> > +A simple binding to represent a set of keys as described in
> > +include/uapi/linux/input.h.  This is to communicate a
> > +sequence of keys to the sysrq driver.  Upon holding the keys
> > +for a specified amount of time (if specified) the system is
> > +sync'ed and reset.
> > +
> > +Key sequences are global to the system but all the keys in a
> > +set must be coming from the same input device.
> > +
> > +The /chosen node should contain a 'linux,sysrq-reset-seq' child
> > +node to define a set of keys.
> > +
> > +Required property:
> > +sysrq-reset-seq: array of keycodes
> > +
> > +Optional property:
> > +timeout-ms: duration keys must be pressed together in microseconds
>
> milliseconds (ms) or microseconds (us)?
>
>
Right, milliseconds.


> > +before generating a sysrq
> > +
> > +Example:
> > +
> > + chosen {
> > +                linux,sysrq-reset-seq {
> > +                        keyset = <0x03
> > +                                  0x04
> > +                                  0x0a>;
> > +                        timeout-ms = <3000>;
> > +                };
> > +         };
> > +
> > +Would represent KEY_2, KEY_3 and KEY_9.
> > +
> > diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
> > index b51c154..01a8729 100644
> > --- a/drivers/tty/sysrq.c
> > +++ b/drivers/tty/sysrq.c
> > @@ -44,6 +44,7 @@
> >  #include <linux/uaccess.h>
> >  #include <linux/moduleparam.h>
> >  #include <linux/jiffies.h>
> > +#include <linux/of.h>
> >
> >  #include <asm/ptrace.h>
> >  #include <asm/irq_regs.h>
> > @@ -671,6 +672,50 @@ static void sysrq_detect_reset_sequence(struct
> sysrq_state *state,
> >       }
> >  }
> >
> > +static void sysrq_of_get_keyreset_config(void)
> > +{
> > +     unsigned short key;
> > +     struct device_node *np;
> > +     const struct property *prop;
> > +     const __be32 *val;
> > +     int count, i;
> > +
> > +     np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq");
> > +     if (!np) {
> > +             pr_debug("No sysrq node found");
> > +             goto out;
> > +     }
> > +
> > +     prop = of_find_property(np, "keyset", NULL);
> > +     if (!prop || !prop->value) {
> > +             pr_err("Invalid input keyset");
> > +             goto out;
> > +     }
> > +
> > +     count = prop->length / sizeof(u32);
> > +     val = prop->value;
>
> None of the existing helpers to retrieve property arrays doesn't work here?
>

The problem here is that we never know how long the sequence will be.  As
such the 'of_property_read_uXY_array' functions won't work.  Or maybe
you're referring to another set of helpers... If so, please clarify.


>
> > +
> > +     if (count > SYSRQ_KEY_RESET_MAX)
> > +             count = SYSRQ_KEY_RESET_MAX;
> > +
> > +     /* reset in case a __weak definition was present */
> > +     sysrq_reset_seq_len = 0;
> > +
> > +     for (i = 0; i < count; i++) {
> > +             key = (unsigned short)be32_to_cpup(val++);
> > +             if (key == KEY_RESERVED || key > KEY_MAX)
> > +                     break;
> > +
> > +             sysrq_reset_seq[sysrq_reset_seq_len++] = key;
> > +     }
> > +
> > +     /* get reset timeout if any */
> > +     of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms);
> > +
> > + out:
> > +     ;
> > +}
> > +
> >  static void sysrq_reinject_alt_sysrq(struct work_struct *work)
> >  {
> >       struct sysrq_state *sysrq =
> > @@ -688,6 +733,7 @@ static void sysrq_reinject_alt_sysrq(struct
> work_struct *work)
> >               input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
> >               input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
> >
> > +
>
> spurious ws change


> >               input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
> >               input_inject_event(handle, EV_KEY, alt_code, 0);
> >               input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
> > @@ -903,6 +949,7 @@ static inline void sysrq_register_handler(void)
> >       int error;
> >       int i;
> >
> > +     /* first check if a __weak interface was instantiated */
> >       for (i = 0; i < ARRAY_SIZE(sysrq_reset_seq); i++) {
> >               key = platform_sysrq_reset_seq[i];
> >               if (key == KEY_RESERVED || key > KEY_MAX)
> > @@ -911,6 +958,13 @@ static inline void sysrq_register_handler(void)
> >               sysrq_reset_seq[sysrq_reset_seq_len++] = key;
> >       }
> >
> > +     /*
> > +      * DT configuration takes precedence over anything
> > +      * that would have been defined via the __weak
> > +      * interface
> > +      */
> > +     sysrq_of_get_keyreset_config();
> > +
> >       error = input_register_handler(&sysrq_handler);
> >       if (error)
> >               pr_err("Failed to register input handler, error %d",
> error);
> >
>
>

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Re: [PATCH v4] Input: sysrq - DT binding for key sequence

[Rob Herring]

On Tue, Jul 16, 2013 at 5:24 PM, Mathieu Poirier
<mathieu.poirier@linaro.org> wrote:
>
>
>
> On 15 July 2013 20:43, Rob Herring <robherring2@gmail.com> wrote:
>>
>> On 07/15/2013 10:36 AM, mathieu.poirier@linaro.org wrote:
>> > From: "Mathieu J. Poirier" <mathieu.poirier@linaro.org>
>> >

[snip]

>> > +     prop = of_find_property(np, "keyset", NULL);
>> > +     if (!prop || !prop->value) {
>> > +             pr_err("Invalid input keyset");
>> > +             goto out;
>> > +     }
>> > +
>> > +     count = prop->length / sizeof(u32);
>> > +     val = prop->value;
>>
>> None of the existing helpers to retrieve property arrays doesn't work
>> here?
>
>
> The problem here is that we never know how long the sequence will be.  As
> such the 'of_property_read_uXY_array' functions won't work.  Or maybe you're
> referring to another set of helpers... If so, please clarify.

What about of_property_for_each_u32? Or we should make
of_property_read_uXY_array work with arrays that can be less than some
max size.

Rob